If using 100 HP takes 7 gal/hr, then 0.7 gal/hr means you throttle
down to 10 HP tops. Nothing magic there. And yes I know, it is
pleasant to dream that if you held your mouth just right, you could be
at the helm of a mighty sea boat again!

Just noticed that typos crept into my fuel consumption post which
should have read ".7 GPM" (gallons per mile) at 1000 RPM instead of gph
(gallons per hour).

If only it were true :-)